Katsumi and Isami were both looked after when they were younger by policewoman Kaoru Komaki. After a long time of being absent in their lives she finally returns to Ayaka City. However, their long-awaited reunion is cut short once Kaoru is kidnapped and trapped within the kaiju body of Mecha Gomora…

The battle between the two Ultra Brothers and Saki Mitsurugi, who transformed into a kaiju, was long and hard with no clear winner. But shortly afterwards, Saki visits the two brothers at Quattro M! Although Katsumi proposes that they all work together to save the world from destruction, Saki refuses to respond, and instead begins to tell them the story behind their mother, Minato Mio’s disappearance! And an inescapable, centuries-old battle will start once again…